Cement issue 2025/7 presents a broad range of interesting articles without a specific overarching theme. This issue includes, among others, a four-part series on the Selectieve Onttrekking (Selective Withdrawal) structure in IJmuiden, as well as articles on the tension between environmental impact and technical service life, on so-called vibe engineering, and on the influence of the static system on bridge bearings.
Selective Withdrawal
Four-part series on the construction of the new salt barrier at the IJmuiden Sea Lock
Authors:
ir. Marc Romans, Van Hattum en Blankevoort
ing. Hugo Vlieland MSEng RC, Van Hattum en Blankevoort
ir. Gerralt Partiman, Van Hattum en Blankevoort
At the New Sea Lock in IJmuiden, a large hydraulic structure has been built: the Selective Withdrawal barrier. This impressive structure prevents excessive inflow of salt water into the hinterland. The project includes, among other elements, abutments, piers and separating walls. The structures were largely prefabricated at a nearby construction yard.
Part 1 – Advanced Lego
Salt barrier prevents salinisation of the hinterland
The New Sea Lock in IJmuiden, the largest sea lock in the world, was opened in January 2022. However, the ingress of salt seawater limits the use of the lock, as each lockage introduces a large amount of salt into the North Sea Canal. For this reason, the world’s largest “salt barrier” was constructed. Through selective withdrawal of salt water, the barrier prevents further salinisation of the North Sea Canal and the surrounding hinterland.
Part 2 – Prefabricated Concrete Piers
Complex reinforcement detailing
The walls separating salt and fresh water in the Selective Withdrawal structure at the IJmuiden Sea Lock are supported in the centre by two piers. These concrete piers were prefabricated at a nearby construction yard and lifted into position using a large crane. Particular attention was paid to loads during transport and to the complex detailing of the reinforcement.
Part 3 – Abutments with Prefabricated Sheet Pile Elements
Hybrid structure transfers horizontal and vertical loads
On both sides of the retaining structure in the Selective Withdrawal system at the IJmuiden Sea Lock – where salt and fresh water are separated – abutments are located, consisting of prefabricated sheet pile elements. These elements were preassembled at a construction yard and then transported by water to their final location. Various structural components ensure proper load transfer.
Part 4 – Separating Walls and Fish Passages
Special attention to bearings and water-tightness
The separation between fresh and salt water in the Selective Withdrawal structure at the IJmuiden Sea Lock is formed by concrete walls with a movable steel barrier in the centre. Openings for fish passages are incorporated in the concrete walls. The walls are supported on special bearing blocks placed within the grooves of the abutments and piers.
Tension Between Environmental Impact and Technical Service Life
CROW Programme Advisory Board for Concrete and Concrete Structures outlines its vision in a positioning paper
To reduce the environmental impact (MKI) of concrete structures, new concrete mixes are being developed. However, the effect of these mixes on the technical service life of concrete is not always fully understood. Continued attention to this tension between sustainability and durability is therefore required, including further research, as stated by the CROW Programme Advisory Board for Concrete and Concrete Structures in a positioning paper.
Vibe engineering: science fiction or reality?
Structural Engineer of the Year (3)
Author:
ir. Rayaan Ajouz, Witteveen+Bos and Bouwen met Staal
In June of 2025, Rob Doomen and Rayaan Ajouz were named Structural Engineer and Talent of the Year, respectively. In a series of columns in Cement, they reflect on key themes in the profession. In this installment, Rayaan Ajouz takes the reader into a future perspective involving so-called vibe engineers, who are able to generate structural calculations using prompts.
Brothers in Concrete
Concrete in focus: Faculty buildings, São José dos Campos / Piracicaba, Brazil
Author:
ir. Kirsten Hannema
For the Brazilian Universidade Anhembi Morumbi, KAAN Architecten designed two faculty buildings in which the concrete load-bearing structure is tailored to the hot climate. The metre-high louvred façades admit daylight while blocking direct sunlight, resulting in minimal need for building services. The architects relied on the expertise of local contractors accustomed to building in concrete. The first building, in São José dos Campos near São Paulo, was cast in situ, while the second, located 200 km away in Piracicaba, was constructed using precast concrete.
Column – Rico Zweers
The forgotten rule of encounter
Where today we speak endlessly about sustainability and efficiency, the focus in the past was on encounter, openness and a sense of community. Only where people truly meet can the imagination arise that is needed to continue building together.
Influence of the Static System on Bearings
Section: Something Learned (2)
Author:
ir. Thomas van Ingen RC, Mobilis
The choice of the static system must be translated into the bearing design of a bridge structure. Insufficient attention to this in the preliminary design phase may lead to undesirable adjustments at a later stage. Various considerations play a role, which are explained using a fictitious example.
The Young Structural Engineer
Author:
ir. Rick Damoiseaux
In this section, we are introduced to Rick Damoiseaux. He discusses one of his first projects, the revision of the rigging manual for RAI Amsterdam, and shares his views on the structural engineering profession.
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